Clean air is legalized, DDT is banned, Pennsylvania dumps its ash in Haiti and India finishes a dam.

Dec. 31, 1972: A nationwide ban on the use of the pesticide DDT takes effect in the U.S. A decade earlier, Rachel Carson’s book "Silent Spring" brought the dangers of the pesticide to public attention. Many bird species, from bald eagles to hummingbirds, are threatened when DDT applications thin the birds' eggshells.

Dec. 31, 1987: After being rejected at several other ports, the cargo ship Khian Sea arrives in Gonaives, Haiti, dumping about a third of its cargo of 14,000 tons of toxic incinerator ash on the shoreline. The ash, originally from Philadelphia, sits in Haiti for over a decade. Eventually, the ash is returned to Pennsylvania and land filled.

Dec. 31, 2006: India completes the Sardar Samovar Dam on the Narmada River after 20 years of planning, protests and construction. A powerful movement rose to oppose the dam, which displaced 320,000 residents.

Dec. 31, 2011: A rare magnitude 4.0 earthquake near Youngstown, Ohio is later discovered to likely have come from an even rarer source: Pumping wastewater from natural gas “fracking” operations back into the ground.

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